Export a single DataTable to multiple Excel sheets using OpenXml in ASP.Net

REF:Export GridView Data to Excel using Open Xml in ASP.Net

Please refer this code

 HTML

<asp:Button Text="Export" OnClick="ExportExcel" runat="server" />

Namespaces

using System.IO;
using System.Data;
using ClosedXML.Excel;

 C#

protected void ExportExcel(object sender, EventArgs e)
{
    DataTable dt = new DataTable("GridView_Data");

    dt.Columns.AddRange(new DataColumn[6] { new DataColumn("Id", typeof(int)),
                        new DataColumn("Name", typeof(string)),
                        new DataColumn("Country",typeof(string)),
                        new DataColumn("City",typeof(string)),
                        new DataColumn("Moble",typeof(string)),
                        new DataColumn("Landline",typeof(string))});

    dt.Rows.Add(1, "John Hammond", "United States", "Washington DC", "111111111", "11111111");
    dt.Rows.Add(2, "Mudassar Khan", "India", "Mumbai", "111111111", "11111111");
    dt.Rows.Add(3, "Suzanne Mathews", "France", "Paris", "111111111", "11111111");
    dt.Rows.Add(4, "Robert Schidner", "Russia", "Moscow", "111111111", "11111111");
    DataTable dt1 = new DataTable("GridView_Data");
    DataTable dt2 = new DataTable("GridView_Data1");
    for (int i = 0; i < dt.Columns.Count - 3; i++)
    {
        dt1.Columns.Add(dt.Columns[i].ColumnName);
    }

    for (int i = 0; i < dt.Rows.Count; i++)
    {
        dt1.Rows.Add(dt.Rows[i][0].ToString(), dt.Rows[i][1].ToString(), dt.Rows[i][2].ToString());
    }

    for (int i = dt1.Columns.Count; i < dt.Columns.Count; i++)
    {
        dt2.Columns.Add(dt.Columns[i].ColumnName);
    }
    for (int i = 0; i < dt.Rows.Count; i++)
    {
        dt2.Rows.Add(dt.Rows[i][3].ToString(), dt.Rows[i][4].ToString(), dt.Rows[i][5].ToString());
    }
    using (XLWorkbook wb = new XLWorkbook())
    {
        wb.Worksheets.Add(dt1);
        wb.Worksheets.Add(dt2);
        Response.Clear();
        Response.Buffer = true;
        Response.Charset = "";
        Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
        Response.AddHeader("content-disposition", "attachment;filename=GridView.xlsx");
        using (MemoryStream MyMemoryStream = new MemoryStream())
        {
            wb.SaveAs(MyMemoryStream);
            MyMemoryStream.WriteTo(Response.OutputStream);
            Response.Flush();
            Response.End();
        }
    }

}

Screenshot

First one is sheet one and other one is sheet two.